My samsung Galaxy S4 GT-I9505 (unlocked) is not coming up. The phone seems to be dead. I tried different batteries,still not working. The phone's battery is working in a different phone. I have taken this to a technician and he told that the issue is with motherboard. The phone had over heating issues when it was charging after I updated it to android kit kat 4.4.2. There was a water damage about 3 months ago, but the phone worked fine after it was repaired. I bought this phone from ebay, I have already contacted Samsung US customer service and they have asked me to contact Samsung Brazil since the phone came from Samsung Brazil. I contacted them they told it has to be taken to a local samsung customer service center in brazil. Any suggestions about how to fix this issue? If I have to replace the motherboard where should I go ?